Today a rapid miniaturization is taking place in electronics. Traditional methods of cooling and cooling devices no longer are able to provide the cooling required for correct operation of the electronics. Another consequence of this miniaturization is that the need for screening of components increase. Higher clock frequencies are used, which increases radiation.
In FIGS. 1a-1c a structure which can be used for obtaining proper cooling and proper screening is shown. As shown in FIG. 1a, the electronic components are located on different levels in a frame comprising cooling flanges. In this tower structure the components are contained in metal cassettes connected to the outer cooling flanges in the common frame. FIG. 1b is a cross section of such a cassette where the different electronic components 101 are shown.
In such a structure shown in FIG. 1a and FIG. 1b, the components are mainly cooled via thermal conduction in the circuit board. Thus, the components generating much thermal heat must be located close to the cassette edge as is shown in FIG. 1c. 
One possibility to increase the freedom in location of the components is to thermally connect the upper sides of the components to the walls 113 of the metal cassette, as is shown in FIG. 2. In FIG. 2, which is similar to FIG. 1b, thermal contact elements 103 are located between the inner electronic components and the housing 113 of the cassette. Such a thermal connection can be achieved in a number of different ways. One way of obtaining such a thermal connection is by means of using a pad or bag filled with liquid. In for example U.S. Pat. Nos. 5,640,303 and 5,720,338 such pads filled with liquid are described in different embodiments.
However, there is a problem securing or fastening such thermal conducting pads filled with liquid. A pad filled with liquid provided to contact one or several electronic components in order to conduct away thermal heat can come out of its proper position. This is of course not desired since a large part of the cooling then is lost, and the component may be overheated.
Its an object of the present invention to provide a fastening element for a thermally conducting pad filled with liquid which securely keeps the pad at the intended position without reducing the flexible characteristics of the pad.
This object and others are obtained by a fastening element comprising a frame on to which a number of individually resilient tongues are attached.
Such an arrangement achieves that a pad or bag filled with liquid securely can be fixed within the frame, while the individually resilient tongues achieves that the desired flexible characteristics of the pad filled with liquid are maintained.